Process of drying lumber



F. K, FISH, liz.

PROCESS 0F DRYING LUMBER.

APPLICATION FILED MAILS, 19H. RUN-:WED DEC. 13| i919.

Patented Jian. 20, M2M

NETE@ STATES PATENT QFBICE.

FREDERK Ii. FXSH, JR., OF NEW YORK, N. Y., ASSIGNR TO LUMBER TIE AND TIMBER VULCANZING COMPANY, DF NEW YORK, N. Y.

PRCESS F DRYING LUMBER.

Specification of Letters Patent.

Application led March 8, 1917, Serial No. 153.488. Renewed December 13, 1919. Serial No. 344.750.

` To all whom it may concern.'

improvements in Processes of Drying Lumber, ot which the followingis a specification.

The present invention is based upon a. proper recognition of the physi 'al characteristics ol" wood and analogous substances, the. chemical constituency or their fluid coutent, and the possibility of converting` into an agency for preservation, certain of' their contained elements, which` under natural conditions, would form the basis of their deterioration or destruction, but refers more particula ly to wood. p

Structur-illy, woodconsists of a skeleton of cellulose. intermingled with other orga-nic substances, collectively designated as lignin, together with a minor proportion of mineral matter or ash. liignin, while not fully understood chemically, is closely allied to the cellulose element of the wood, and since it forms a part of the permanent structure of the wood, it may, tor purposes of the present invention, be regarded as identical with the cellulose.

'lo utilize the natural bases of resin, acetic and tannic acid, existing in wood, as preservatives ot the wood, it is necessary that they be dislodged from their cellular confinement, separated from their aqueous solvent or vehicle, converted by oxidation and properly distributed through or deposited upon the cellular and fibrous structure of the wood.

l ain aware that certain patents have been obtained for drying` wood with free steam, and heat under vacuum. By these methods wood may be dried but they require such a length ot' time to accomplish an ideal and uniform product as to make them uncommercial, from a lumbermans viewpoint and cost such a large amount of money that such a process would not have any commercial value. lt the time required to treat Wood under such a process were reduced to a point where the methods would produce an amount of wood which would make it of interest to the lumber manufacturer, the heat lin the sterilizer under the vacuum step would be of a degree that would cause the removal from the lumber of the preservatives of the wood, and therefore, decrease very materially the value ot' the wood. In addition to which, the shrinkage in the wood would be great and excessive and the wood would be rendered brittle and where in close contact with the heating coils, would be discolored. In the method herein specified, the vacuum step is tor such a shoit length o time that' only the surface moisture is removed and the resinJand gums are distributed upon the liber of the wood.'

One of' the objects ot the herein set forth process is the reduction of time required for drying wood and analogous substances; a further Objectis the drying of certain destruct-ible substances from which the evaporate may be obtained.v A still further object is the treatment of wood in such manner as to fix therein such natural substances of the wood as may be desirable.'

liv way of teaching the invention more in detail, one approved method of practising the same will be described with reference to the accompanying drawing, in which Figure l is a vertical longitudinal section of a sterilizcr, suitable for carrying out the erably provided with a. presser plate 9. with adjusting screws 3, through meansot which the charge o'l wood may be kept under pressure while being treated. lt is alsoprovided with heating coils lby which the temperature of the atmosphere or steam within the sterilizer may be heated to the desired degree, and with coils 5 which may be perforated for the purpose of supplying free steam within the sterilizer when desired. The sterilizer is also provided with tracks (i for the convenient introduction of a truck load of lumber thereinto. 7 is an exhaust pipe provided with any approved valve for opening land closing it. To equip the sterilizer 1 for lconveniently developing the several conditions incident to the several steps of the process, it is provided with an eX- haust pipe 8 leading to a vacuum pump 9, with an interposed condenser 10.

wood.

l The releese und 'convoi'sion :the sibstenees es peoiully the mostI importent them, namely, ,the Volatile oils wliioli,'when oxidized, :forni resin, lis ueeomplishe 'l, ec cording to niy iiwdntion, by first subjecting the Wood to heiiuthen placing the wood in e'steiilizer Whiel'i is capable oi' heilig herineticelly -elosed,l then introducing' free steam 'into the sterilizer under pressure, the

'temperature und pressure'witlnn the steri lizer varying :iceording to 'the requirements of the substance operated upon in such ina-nner 'as to prevent injury to the materiel' being treated, sin'uiltzuieously introducing steam in the heating coils within the sterivlizer until the desired temperature und pres sure is obteined--and inuintuinin-g the teni peinture for such period ofvtiine es muy be found to be suitable to the'nmteriol to be operated upon.

At the desired moment u Vacuum is created Within the'sterilizer by the operation of the vacuum ump.. lf it is advisable to obtain the disti late, @surface Condenser is preterzdile. Simultaneously, all ineens used to bring the 'inter-lor ot the sterihzer .under pressure are operated in suoli manner and to sucheXtent as 1s found desirable.

.oftiine depending upon the materiel being treated und the condition ol the moisture contained therein. The flow et heating fluids or gases is out olf from the radioting pipes et this stage of the process und the materiul, after cooling Withinv the sterilizer, is Withdrawn therefrom.

if' Under certain conditions it muy be desir- Vable 'that the transition from pressure to vacuum' be extremely gradual in order" to maintain the' desired conditions of the niediuln surrounding the materiel being; treated, especially, With regard to the degree oi saturation thereof.

In order that my process may be more fully und better understood, l Will recite in detail 'the several steps thereof in the drying' 1"X2 Cypress lumber, which ordinarily requires from sin to lseven days, to dry in the ordinary kiln to shippingl weight, which is about threedii'ths oi? the Weight of green The Wood is iirst placed in u. sweut ehuniher, (not shown) lund heut then introduced into seid ehunihezgwhieli muy Ibe eonveniently sind eoononiioully done ily convey-- ing the 2i/este und steers from the eral pleut intothe olniinherv 'by any suitulole i ineens; this heut step renders the wood more receptive to the notion ot the free steuni; then the Wood being stacked on e truck, with 'stickers placed between the layers thereolE and run into the sterilizer 1. The sterilizer is then closed und, steam is turnedinto the heating coils et, say, one hundred pounds pressure. The din-in or exhaust 'valve 7 lending `from. the sterilizer being opened, stezun is then gradually' introduced into sterilizer 1 through perforated pipes 5 until the Wood is heated und the steam be Tins to pass out through valve 7, vulve 7 then elosed und the pressure in.' the sterilizer raised to, say, thirty pounds shove utmospliere, this pressure being n'mintuined for vepprr'ixirnitely one hour liy 'admitting' steam at thirty pounds pressure through pei-'forated pipe rl`hen vulve Y is opened end the pressure in the sterilizer allowed to drop slowly und gradually, say, ut the rate oi' three pounds per hour :it the beginning of the said reduction oi' pressure, stezun being continuously adi'nitted through perforated pipes 5 to maintain this drop, heating coils Il being operated at such ten'ipeinture as will insure dry, saturated steiun inthe sterilizer during the drop of pressure.` As the decreuse' of pressure continues the rute there of is reduced, shy, when ten pounds above atmosphere' is rea-shed, the, rete of 'de-` creased pressure is mui'nteinedet two pounds perhour. This 'reduction is veon'tii'iued until the pressure is redueed to say, ten pounds, below atmosphere, or five pounds ubsoiute. At the state of this final reduction of pressure a slight heating takes place es e. temperature of say, 20Go F. is maintained; the boiling point is about 126 F. he heat is then. cut oil from the heating coils, also the steam from'-perforated pipes 5, the vacuum is maintained forsome time during the cooling until. 'the heet drops below the saturation temperature, when the vacuum is broken und the Wood allowed to cool under its contained heet.

The 'Wood will now he thoroughly dried Without removing the 'velues ot its sep; 'the latter will be converted especially as to its volatile oils, into resin; 'this resin having permeated the entire cellular structure of the Wood, While the moisture was still pres-v ent and the pores opened up and temper- :it-ure high will have precipitated upon or surrounded the cell wells or fibers now that the moisture has departed. Thus, the Wood has been rendered homogeneous throughout, indureted, y sterilized, end rendered less hygrosoopio (md correspondingly in'nnune from spores or fermentation. or the like. .lind'ell these conditions ere attained With-l out checking, warping, oase hardening or other deterioration of the physical Chers@ teristics of the Wood. l

From the foregoing, it will be seen that 'he ust essentie eendit'en to be predueed 1s the thoxough seenmg and opsnmg up of the Weed stfuetme and the dissolvimg 01" its gummy sep matters and freeing them from their ceminement, so that they een be disrbuted through the'weod strucure.

1. The emesse of dwing wood, ,which consists suomtng thewoed'i te e meflel ately heated, meist atmosphere Whou; pressen; then 'te a body of steam under pressure until its peres are opened up and its gummy ssp metiers dissolved; then grudnally reducing the pressure te below atmspherc pressure While simultaneously sup pyng heet; inaily drying at stmosph'emc pessu'le md Wthew hem.

'2. The process of rylng weed, Whcg `cmlsists in pecng the Wood in a mederately heeted, meisf'a atmosphere Without pressure; hen'sfo steam Under pressure until,

its are opened .up and its gummy sep wettexg disseved; the-n reducmg the pressure to below atmospheric pressure Whe' xmnteinng the steam at" a superheeted atmospheric pessaiae.

3. The process of drying Weed Yemen Consists in subjecing the Weed 155e weder-- 35 utely heated, meist etmesphee 'wihemg pressure; hen toe body sii? seem et mbstantafy the dew @eins m'st iss pores are epe'ned up eed its @u nzm/ m* nmte's' dissolved; then ggmdusy feds the pressule fm beleef etmesphee psess'utre; finay drying as aimes@ pressme amd Wilthomj heat.

4. The px'ecess dej/' Weed? cbnssts in first sweating me 'Weed im e; mef'emtey heaed, moisi; s'fmesjglfhees; mee subjecting it to e bed"e? 'endete pr. sure until poses MJ epenec s@ e? with? dre-wing moist/me Miele ing the pressure te kv sue; nely drying, l md 'andere she Weee's YM e 

